Carboxyl containing polymers of vinylidene monomers containing at least one terminal CH.sub.2 .dbd.C&lt; group are known. Such polymers may be homopolymers of an unsaturated, polymerizable carboxylic monomer such as acrylic acid, maleic acid, itaconic acid and the like, or copolymers thereof. Typical materials are those described in U.S. Pat. No. 2,798,053. For example, copolymers of acrylic acid with small amounts of polyalkenyl polyether cross-linkers are gel-like polymers which, especially in the form of their salts, absorb large quantities of water or solvents with subsequent substantial increase in volume. Other useful carboxyl containing polymers are described in U.S. Pat. No. 3,940,351, directed to polymers of unsaturated carboxylic acid and at least one acrylic or methacrylic ester where the alkyl group contains 10 to 30 carbon atoms which are efficient thickening agents in aqueous solutions, even in the presence of substantial amounts of inorganic salts. Other types of such copolymers are described in U.S. Pat. No. 4,062,817 wherein the polymers described in U.S. Pat. No. 3,940,351 contain additionally another acrylic or methacrylic ester and the alkyl groups contain 1 to 8 carbon atoms. It is difficult to polymerize such materials in the usual solvents, because of swelling and gel formation, and such materials have normally been prepared in hydrocarbons and chlorinated hydrocarbons, for example, benzene, xylene, tetralin, hexane, heptane, carbon tetrachloride, methyl chloride, ethyl chloride and the like. Polymerizations are disclosed, for example, in 4,062,817 wherein the polymerizations are desirably conducted in the presence of haloethane or halomethane, preferably containing at least 4 halogen atoms. For example, 1,1,2-trichloro-1,2,2-trifluoro-ethane. Other carboxyl containing polymers prepared in similar systems include those described in U.S. Pat. No. 3,915,921 and 4,066,583. A number of solvents used and suggested in the prior art are toxic. An improved method for preparing and easily recovering the carboxylic containing polymers in non-toxic polymerization systems is desired. In the past the requirement that the polymerizing solvent should not swell the precipitated polymer for ease of polymer recovery has limited the use of solvents to non-polar or slightly polar solvents having low solubility parameters.